This thesis is devoted to theoretical and experimental studies of the basic device of photovoltaic conversion : the solar cell. First, renewable energies are highlighted in a general introduction and ... [more ▼]

This thesis is devoted to theoretical and experimental studies of the basic device of photovoltaic conversion : the solar cell. First, renewable energies are highlighted in a general introduction and their economic, ecologic and environmental advan- tages in comparison with fossil energy resources are emphasized, then, a revue of structure, types of bonds and energy bands of a solid material is presented and the case of a semiconductor is considered. Starting from Maxwell equations, the basic semiconductor equations namely Poisson’s equation and the continuity equations of electrons and holes are established. Next, discretizations of Poisson’s equation using a finite difference scheme and of the continuity equations by the Gummel-Scharfetter scheme are performed. The obtained system of equations is solved iteratively according Newton-Raphson algorithm. The experimental part of the work, entirely achieved in LIOS affiliated to JKU at Linz (Austria), aims the fabrication and the characterization of organic bulk heterojunction solar cells based on two different polymers used as donors P3HT and AnE-PVstat and the molecule PCBM as acceptor. A comparative study of the fabricated solar cells indicates that the device efficiency depends on the donor:acceptor ratio. In or- der to understand electronic and optical mechanisms occurring within a solar cell and which may affect its characteristics and performance, and to identify the role of the equivalent circuit parameters describing these mechanisms, many electronic circuits modelling the solar cell are presented and only the five physical parameters circuit is chosen. Several physical parameters extraction methods are exposed in details and only three of them are retained to extract the five physical parameters of the fabricated solar cells. The effects of each physical parameter on the solar cell efficiency are investigated. Thus, the variation intervals of the photovoltaic metrics, fill factor and efficiency under the influence of parameters variations can be identified. [less ▲]

The climate change crisis and the running out of fossil resources are motivating the use of renewable energies. Solar energy is the main source of the renewable energies and photovoltaics is one of the ... [more ▼]

The climate change crisis and the running out of fossil resources are motivating the use of renewable energies. Solar energy is the main source of the renewable energies and photovoltaics is one of the main ways of photon conversion. This alternative energy is safe, clean and abundant. The purpose of this paper is the use of Maple software in: - Determining, without any approximation, the model physical parameters of real photovoltaic solar cell as a basic element of photovoltaic conversion. - Analyzing the effects of each physical parameter on real solar cell current-voltage characteristics and output power curve. [less ▲]

Photovoltaic energy is one of the most important renewable energies. This type of energy, unlike other energy sources, is clean, safe, and abundant. The photovoltaic solar energy is based on the ... [more ▼]

Photovoltaic energy is one of the most important renewable energies. This type of energy, unlike other energy sources, is clean, safe, and abundant. The photovoltaic solar energy is based on the conversion of sunlight into direct current by solar cells. In order to increase the efficiency of the photovoltaic conversion and for a better understanding of the solar cell behavior, an accurate knowledge of the cell physical parameters is required. In this work, the solar cell is considered as a generator and the one-diode equivalent circuit is retained. This electronic circuit modeling the solar cell contains a diode with its reverse saturation current and its ideality factor, parasitic series and shunt resistances and a photocurrent generator. In this paper, a new physical parameters extraction method is presented, for the first time to our knowledge, which is based on the current-voltage characteristics and on the analytical expression of the output voltage given in term of the Lambert W function. This method gives all the physical parameters without any approximation or introduction of initial values. To test the efficiency of the presented method, a comparative study with other extraction methods is done. The obtained results are in good agreement. [less ▲]